"Perhaps," said Williams with electrifying logic, "it's a gang habit. No identification if they're caught."
That was a possible theory, and Grant was silent for a little, thinking it over. It was with the entrée that he became conscious, with that sixth sense which four years on the western front and many more in the C.I.D. had developed to an abnormal acuteness, that he was being watched. Restraining the impulse to turn round — he was sitting with his back to the room, almost facing the service door — he glanced casually into the mirror. But no one seemed to be taking the slightest interest in him. Grant continued to eat, and in a moment or two tried again. The room had emptied considerably since their arrival, and it was easy to examine the various people in the vicinity. But the mirror showed only a collection of self-absorbed people, eating, drinking, and smoking. And still Grant had that sense of being subjected to a long scrutiny. It made his flesh creep, that steady, unseen examination. He lifted his eyes above Williams' head to the screen that hid the door. And there, in the chink between the screens, were the eyes that watched him. As if conscious of his discovery, the eyes wavered and disappeared, and Grant went serenely on with his meal. A too curious waiter, he thought. Probably knows who I am, and just wanted to gape at any one connected with a murder. Grant had suffered much from the gapers. But presently, looking up in the middle of a sentence, he found the eyes back at their examination of him. This was too much. He stared stolidly in return. But the owner of the eyes was evidently unaware that he was visible at all to Grant, and continued his watching uninterrupted. Now and then as a waiter came or went behind the screen the eyes disappeared, but always they returned to their furtive gazing. Grant was seized with a desire to see this man whose interest in himself was of so absorbing a character. He said to Williams, who was seated not more than a yard in front of the screen, "There is some one at the back of the screen behind you who is taking a most abnormal interest in us. When I click my fingers fling back your right and knock the screen sideways. Make it look as much like an accident as you can."
Grant waited until the waiter traffic had lulled for a little and the eyes were steady at gaze, and then gently snapped his middle finger and thumb. Williams' brawny arm shot out, the screen quivered for a moment and collapsed sideways. But there was no one there. Only the agitated swinging of the door showed where some one had made his hasty exit.
Well, that's that, thought Grant, as Williams was apologizing for the accident with the screen. You can't identify a pair of eyes. He finished his dinner without further annoyance and strolled back to the Yard with Williams, hoping that the photographs of the prints on the envelope would be ready for his examination.
No photographs had come, but there was a report on the tie which had been sent to Faith Brothers' factory at Northwood. The only consignment of that pattern of tie sent out in the last year was a box of six in various shades which had been sent as a repeat order at the request of their Nottingham branch. They returned the tie and hoped that if they could be of any further use the inspector would command them.
"If nothing important turns up between now and tomorrow," said Grant, "I shall go down to Nottingham while you are doing the banks."
And then a man came in with photographs of the envelope prints, and Grant took from his desk the photographs of the other prints in the case the prints of the dead man's fingertips and the prints found on the revolver. Nothing but smudges, the report said, had been found on any of the bank-notes, so Grant and the sergeant applied themselves to the examination of the envelope prints. A variety of impressions were apparent since several people had handled the envelope since the writer had posted the letter. But clear and perfect and without possibility of doubt was the print of a forefinger to the right of the flap, and the forefinger was the same forefinger that had left its mark on the revolver found in the dead man's pocket.
"Well, that fits your theory about the friend who supplied the gun, doesn't it?" said Grant.
But the sergeant made a queer choked noise and continued to look at the print.
"What's the matter? It's as clear as a kid's alphabet."